The present exemplary embodiment relates generally to a printing system comprising at least two marking engines and more particularly to a modular printing system in which a custom color marking engine module can be temporarily substituted for an existing marking engine module for custom color printing by the system.
Lithographic printing processes typically have a separate marking station for applying inks in each of the four primary colors: cyan, magenta, yellow and black (CMYK). By laying down combinations of these colored inks on print media, different colors and tones are achieved. Where accurate color rendition is required, one or more additional marking stations are added in the process line for custom color inks. The print media to be printed passes through each of these marking stations.
In a typical xerographic marking engine, such as a copier or printer, a photoconductive insulating member is charged to a uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member, which corresponds to the image areas contained within the document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with a developing material. Generally, the developing material comprises toner particles adhering triboelectrically to carrier granules. The developed image is subsequently transferred to a print medium, such as a sheet of paper. The fusing of the toner onto paper is generally accomplished by applying heat to the toner with a heated roller and application of pressure. In multi-color printing, successive latent images corresponding to different colors are recorded on the photoconductive surface and developed with toner of a complementary color. The single color toner images are successively transferred to the copy paper to create a multi-layered toner image on the paper. The multi-layered toner image is permanently affixed to the copy paper in the fusing process.
Xerographic printers do not have the facility to add an extra marking station for custom color in the way that lithographic machines do since the color stations are in fixed locations around a photoreceptor of limited length. Where a custom color is to be applied, this is often achieved in a separate lithography process, prior to xerographic printing with the four primary colors. As a result, a xerographic printer may need to have on hand a variety of preprinted paper stocks which are fed to the xerographic printer when a particular customer's order is to be printed.